Up: Configurations and Target Data
The parameters specified below define the target position and rotator
- Target name and position
- in any of the coordinate systems supported
by the WHT telescope control system. The following parameters are
The remaining parameters are optional. Parallax and radial velocity, in
particular, will make very small differences to the exact selection of
guide stars and to the computed guide probe positions, but are retained for
consistency with the TCS and to allow direct use of WHT catalogue files.
- Right ascension
- Hours, minutes, seconds, separated by spaces.
- Degrees, minutes, arcseconds, separated by spaces.
- Mean FK4 or FK5 systems (e.g. B1950, J2000) or apparent
coordinates of arbitrary date. (Note that this is a change from the WHT
TCS, which supports apparent coordinates of current date only. This is
necessary in order to allow running of the guide star search software
well before the observations take place).
It is possible to input target positions in a catalogue file in
the format accepted by the WHT control system. In this case,
references to a particular object are by name. The catalogue format is
described in detail in Section 7.1.
- Proper motions
- in RA (seconds of time per year) and Dec
(arcseconds per year). Defaults to zero.
- (year). Defaults to equinox.
- (arcsec). Defaults to zero.
- Radial Velocity
- (kms; defaults to zero).
- Rotator position angle
- This is a sky position angle, in the range
- , as used by the relevant telescope control system.
See Appendix A.2 for some subtleties affecting wide fields.
Mon Mar 1 17:52:09 GMT 1999